This is a proposal to advance the state of acoustic microscopy in the biomedical field. The work will be divided between an investigation of biological cells with the acoustic beam as it exists in the present instrument and the improvement of the instrumentation so as to increase our ability to extract information from the images. We will concentrate primarily on the contractile processes in cells since that is one area where the elastic processes are dominant. The work on the instrumentation will allow us to record images with improved resolution. We also want to be able to study the cells in different environments and at different temperatures. We plan to work with several acoustic frequencies and the work on instrumentation will be aimed toward these goals.